Why is the King visiting Trump and the US, and what will he do?
Visit set to stress the strength of the historical military ties between the United States and the United Kingdom
The King and Queen fly to the US today for their state visit, the first to the country since Queen Elizabeth II's visit in 2007.
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It comes just two days after Donald Trump was targeted in another assassination attempt.
On the agenda for day one is a private afternoon tea with the Trumps, followed in time-honoured royal tradition by a garden party.
Amid mounting speculation around the trip, the White House and Buckingham Palace confirmed Charles and Camilla will be "very safe" and, while some changes have been made to the royal itinerary, it will go ahead largely as planned.
The royal couple arrive in the US on Monday, 27 April, and will visit Washington DC, New York and Virgina before flying home on 30 April.
Here's what we know about how the four-day visit will unfold:
Follow LBC's live blog of the King's visit here.
Arrival in Washington DC
King Charles and Queen Camilla will arrive in Washington DC on Monday after directly flying from the UK at around 4.15pm local time (9pm BST)
They will be welcomed by their hosts, President Trump and his wife Melania, with a private afternoon tea before receiving a tour of the newly expanded White House Beehive on the South Lawn.
Later on there will be a garden party at the British ambassador's residence which will bring together a "wide variety of guests representing the connections between our two countries", according to Buckingham Palace.
Read more: How will Donald Trump treat King Charles on the state visit?
Garden parties are a regular feature of state visits, although the British Royal Family have not attended one in the US since 1939, when King George VI and Queen Elizabeth held a garden party at the embassy in Washington.
Formal welcome and military review
On Tuesday, the royal couple will head to the White House for a formal welcome from the Trumps, followed by a ceremonial military review.
Another staple of British state visits, ceremonial military reviews are a tradition dating back to the 18th century.
Read more: Trump insists King Charles 'would have stood by him' on war with Iran
The US Marine Band will play the national anthems of both countries, and the Presidential Salute Battery will perform a 21-gun cannon salute.
Mr Trump will deliver a short speech on the South Lawn before thousands of guests including cabinet members, the official UK delegation, military families and Congress members.
There will be an exchange of gifts between the Trumps and the royal couple, and Charles and Camilla will then greet dignitaries from both countries.
It is understood the visit will stress the strength of the historical military ties between the United States and the United Kingdom through two world wars, rather than the present disagreements straining the relationship.
The president last week threatened to investigate the British rule of the Falkland Islands in retaliation for the UK being initially unwilling to allow American forces to use their airbases.
Mr Trump has also hit out at Britain over its response to the Iran war, describing Prime Minister Keir Starmer as cowardly and "no Winston Churchill".
Britain initially blocked the US from using its bases to attack Iran, but following retaliatory Iranian airstrikes, it relented and allowed defensive operations to “protect British interests”.
The US President also hit out at NATO members for not supporting him in his fight to reopen the Strait of Hormuz, which was closed by Iran in response to the US-Israeli strikes.
Read more: Iran offers to reopen Strait of Hormuz despite postponing US nuclear talks
Read more: Starmer to chair ministerial meeting focused on economic impact of Iran war
Charles and Camilla to briefly split ways
After the ceremony the royal couple will briefly part ways, with King Charles and Mr Trump to hold a bi-lateral meeting while the Queen will spend time with the First Lady.
Camilla and Melania Trump will attend an AI educational event, where American students will learn about the histories of both countries using AI headsets and glasses.
King to deliver speech at Congress
Also on Tuesday, King Charles will deliver a speech to both houses of Congress- only the second time a British monarch has addressed a joint meeting of the US legislature since his mother Queen Elizabeth spoke there in 1991.
State dinner
The Trumps will host an official state dinner for the Royal Couple on Tuesday evening in the East Room of the White House.
Both the King and Mr Trump will make speeches, amid concerns over the security of the trip following the attempt on Trump's life during the White House Correspondents' Dinner in Washington on Saturday night.
The White House and Buckingham Palace were locked in emergency talks after a gunman burst into a dinner attended by Mr Trump in Washington DC.
The US president has said that the White House is ‘really safe’ for the upcoming visit, and in a statement released on Sunday, Buckingham Palace confirmed the King's visit would take place with "adjustments" following the developments.
The royal couple to head for New York
After two days in Washington DC, the King and Queen will leave for New York.
They will start with a visit to the 9/11 memorial to recognise the 25th anniversary of the 9/11 attacks, which Buckingham Palace described as "a poignant moment in our shared history".
The royal couple will meet with first responders and the families of victims.
The Mayor of New York Zohran Mamdani is also due to attend, however he will not meet privately with the King, according to his office.
Then the pair will briefly part ways, with Charles scheduled to meet with a mentoring group which works with young people impacted by food insecurity, while Camilla will attend a literature event marking the 100th birthday of Winnie the Pooh.
They will reunite at an event in the evening focused on the creative industries - which could be attended by some famous faces, although no names have been confirmed yet.
The trip concludes with a visit to Virginia
After leaving New York the King and Queen will go back to Washington to say goodbye to the Trumps on Thursday. They will lay a wreath in honour of fallen soldiers from both countries, to mark the US and UK military alliance.
The final leg of the visit will involve a trip to Virginia where the royal couple will attend a party celebrating the 250th anniversary of American independence.
Charles will meet one of the area's Indigenous communities during a visit to a national park, along with others involved in conservation initiatives - reflecting the King's long-standing interest in environmental issues.
The Queen will visit a farm where she will speak about the US horse racing industry and its links to the sport in the UK.
After leaving the US the King will head to Bermuda, where he is also head of state - his first visit as a monarch to a British overseas territory, before returning to the UK
Who isn't included in the itinerary?
The notable absence is the King's younger son, Prince Harry, who lives in California with his wife Meghan.
The royal couple also won't be meeting with the victims of Jeffrey Epstein, amid the scandal surrounding the King's brother Andrew Mountbatten Windsor's friendship with the late convicted paedophile.
Andrew was released under investigation from police custody in mid-February after being arrested on suspicion of misconduct. He denies any wrongdoing.
US Congressman Ro Khanna has called for the King to meet survivors of Epstein, as has the brother and sister-in-law of the late Virginia Giuffre.
It is understood that this could make it complicated for Charles to meet with victims because he would not want to be seen to influence that investigation.